There are a large number of devices and products where two or more components are to be connected and attached to each other, preferably in a non-reversible manner. This could for example be the case for a device comprising an outer housing having a number of components arranged inside said housing. For various reasons, the housing may comprise a number of housing parts. This could for example be the case when assembling and placing the components inside the housing, which is facilitated or enabled by dividing the housing into several housing parts.
When the housing parts are to be attached to each other, it is often desirable to have a connection between the parts that on the one hand makes it relatively easy to assemble the parts and on the other hand makes the connection irreversible. That is, it should not be possible to disconnect the housing parts from each other at least not without using excessive force.
On the other hand, when manufacturing parts that are made of plastic material and produced with standard injection moulding techniques, the geometries and the designs of attachment members must not be too complex and/or too many, since this would adversely affect the moulding forms and the use and complexity of mould cores, just to mention a few aspects.
Document WO2005/044348 discloses a common attachment solution where the parts to be connected are tubular with a generally circular cross-section. One housing part is arranged with a number of circumferentially extending recesses or grooves on its inner surface and the other housing part is arranged with a number of circumferential, radially extending protrusions on its outer surface, where the protrusions have profiles which are complementary to the shapes of the grooves. When assembling the two housing parts, the two parts are pushed together. The protrusions will then press radially on the inner surface of the housing part with the grooves until the protrusions enter the grooves and the two parts are locked together.
Even if this connection works well there are a number of drawbacks. A major drawback is that it requires quite a lot of force because of the friction between the protrusions and the inner surface of the housing part when the housing parts are pushed together. This pushing action thus requires some flexibility of the protrusions as well as the housing parts in the radial direction in order to enable the connection, but even so, there is a pronounced risk of permanent deformation of components due to the force exerted between them. On the other hand if the dimensions are chosen such that the radial force between the protrusions and the housing part is lowered, there is a risk that the final connection is not tight enough and that there may even be play in the connection if the tolerances are not small enough.